using ":slug/edit" without valid user session does not redirect to post edit page after login

[kabukky]

As written by @blockloop in #65 :

In Ghost, when viewing a blog post you can append "/edit" to the end of the url to edit it (assuming you're logged in). This adds that ability to Journey. The only problem I found was as follows.

1. User is not logged in
2. User appends /edit to blog url
3. User gets sent to login page
4. User logs in
5. User sees admin page instead of going to edit post page

This is caused by the usage of the # fragment which isn't carried across the login page. I tinkered with fixing it but r.URL.Fragment was always empty in all handlers. I imagine this is a good first step even without that.